Comcast headquarters in Philadelphia. Comcast is the nation’s second-biggest cable TV provider and a part owner of Hulu.

WASHINGTON • Comcast, the nation’s second-biggest cable TV provider, poses “a much greater threat to competition” than AT&T’s recent merger with Time Warner — and the Justice Department should open a formal investigation, according to a collection of small and independent cable companies.

The request to the Justice Department by Comcast’s rivals adds renewed pressure on the agency to revisit Comcast’s 2011 merger with NBC, a deal that critics said opened up numerous opportunities for anticompetitive misconduct.

For years, a number of government restrictions attached to the deal had limited Comcast’s ability to harm consumers, the letter by the American Cable Association said. But those restrictions expired over the summer, the group said, opening the door to questionable business tactics such as withholding NBC’s television programming from competing cable providers.

“Without any conditions, Comcast-NBCU can act with impunity, and DOJ should expect this to happen,” ACA wrote in the letter, released on Monday. “We have heard from ACA members that they fear that ComcastNBCU may restrict, if it is not already restricting, their ability to access Hulu.”

Comcast is a part owner of Hulu, along with Disney and 21st Century Fox.

Comcast on Monday called the letter an “inappropriate attempt to gain leverage in the commercial marketplace.”

“The video programming and distribution markets are incredibly competitive,” the company said in a statement. “New programmers and distribution platforms are offering consumers increasing choices on what and where to watch. At Comcast NBCUniversal, we are competing in this dynamic environment the way we always have — by continuing to innovate and conducting our business in compliance with antitrust laws and other legal requirements.”

The Justice Department did not immediately respond to a request for comment. But the law enforcement agency warned Comcast in a letter this summer that it will continue to watch the company’s behavior closely now that the merger restrictions have expired.

The deliberate decision to put Comcast on notice is unusual, and reflects the agency’s own concerns about possible antitrust violations, said Gene Kimmelman, a former Justice Department antitrust official who now leads the consumer advocacy organization Public Knowledge.

“The fact they said they’re watching closely is more than they say when other consent decrees expire,” said Kimmelman.

Load comments